914 JOURNAL OF TITE ROYAL HORTICULTURAL SOCIETY. 



rarely grow. They are provided with a coma having barbs for adherence. 

 The leaves are auricular and semicircular in cross-section, densely clothed 

 with overlapping peltate, absorbing scales. When saturated the circum- 

 ference rises, but in drought they are flat on the epidermis, and so check 

 transpiration. 



There is much reduction in the mechanical tissue ; so that the leaves 

 resemble submerged ones in this feature and in their absorbing superficially. 



The guard-cells are massive and permanently closed. 



The slender stems have a dense sheath of sclerenchyma fibres around 

 their fibro-vascular bundles. This has a commercial value for stuffing 

 purposes, forming a hair-like mass. — G. H. 



Timber : Cross-tie Forms and Rail Fastenings, with Special 

 Reference to Treated Timbers. By Hermann von Schrenk {U.S.A. 

 Dcj). Agr. Bur. For., Bull. 50). — With rising prices and gradually 

 diminishing supplies the timber trade of the United States can hardly be 

 said to be in a very satisfactory state. To those interested in railway 

 timbers the present work will be of greatest value, the tie forms, rail 

 fastenings and tie-plates, with the tests of the comparative pulling strength 

 of various spikes, being carefully recorded. 



The illustrations, which are numerous and cleverly executed, should 

 prove useful in further elucidation of the text, there being five plates and 

 seventy-one text figures. 



With the decrease in the timber supply, the question of substitutes in 

 the shape of granite and concrete is discussed, and may in the near 

 future lead to a lessening of the wood supply. — A. D. W. 



Timber, Dry Rot of (Nat. Zeit. Land-Forst. vols. i. and ii. ; 

 1903-4). — Two important contributions on some of the Dry Rot pro- 

 blems already referred to (Journ. R.H.S. May 1904, p. 644). Prof. 

 K. v. Tubeuf (i. pp. 249-268, 2 plates) describes his observations on 

 pure cultures of Meritlius lachrymans grown on gelatine and other 

 nutritive substrata. The photographs of Petri dish cultures show how 

 different media influence the growth. Full nutrition (e.g. malt extract, 

 beef extract, &c., in gelatine) gives the best results if the medium is acid ; 

 but if it is alkaline growth is poor. 



Lieut. B. Malenkovic (ii. pp. 100 109 and 160-168, 1 fig.) describes 

 the germination of the spores of Merulius, and figures them. Germination 

 took place only in acid solutions (1-2 p.c. citric acid) with malt extract, 

 with or without meat extracts and phosphates. The spores did not 

 germinate in many other media tried, and bacterial growths were always 

 fatal to germination. — W. G. S. 



Timber, Fungi on. By P. Hennings (Zeit.f. Pfianz. \iii. pp. 198 



205, 1908). — The author considers that the number of Agaricinecs 

 recorded as parasitic on living trees in the text-books is incomplete. 

 From his own observations, he gives a list of about thirty native Agarics 

 M which occur as partial parasites on tree-stems and timber," with short 

 notes on each. The notes are too brief to give much information, except 

 that the fungi were found on all kinds of timber: living stems, tree 



